I've been an occasional browser for the past few years and it's just lately that I've read GZ regularly. Impressed by what seems to be NZ's most informative forum for tech stuff - seems to be a great crowd here.
I'm hoping to get some ADSL-related advice. I've been with Orcon for many many years and am still on one of their legacy ADSL2+ plans... 12GB + Homeline for circa $80 monthly, with each extra GB being $2. I realised when I got on here that our internet usage is actually far lower than most, but we do end up paying for at least a few extra GBs every month. I've decided it's time to quit the Orcon plan and move; I have a fair idea of my options - Orcon's and Telecom's new plans and perhaps Snap (but this has become less competitive after Orcon and Telecom released their new plans.
Firstly though, I need to figure out why our speeds are absolutely terrible:

The house has a monitored alarm from the previous owners. It's no longer being monitored but the phone line passes through the alarm panel, and there are 3 phone jacks - one goes to the modem, one goes to a filter which our analog phone plugs into, and the other is unused. I have tried removing the filter and analog phone - this resulted in an increase in download speed of approx. 1Mbps and similarly for upload. I have tried removing the lines from the alarm panel but this resulted in all the wall jacks going dead, so I am unable to get an idea of whether speed would increase if it bypasses the alarm panel.
I understand I could get a master splitter installed which should increase speed, but would it even be possible for that to increase speed to 10+Mbps (which seems to be easily attainable from the posts I have seen on here?). Is there anything else I need to test, or do I have to try the master splitter route and see?
My other consideration is the ISP - Orcon's new deals seem great, but they are VoIP plans. I am open to going VoIP but it's new to me and I feel I haven't done enough research into it (such as what phones to get) and I don't really want to just hop on the default Genius bandwagon. I'm tempted to go Telecom just because theirs are POTS deals, so in the event we want to get our alarm monitored, we can do so easily. I'm not averse to getting a alarm if a good one that is fully compatible with VoIP exists, but again I haven't done much research into this. I also know people in the area who are getting good speeds with Telecom and am hopeful that it is the ISP that's the problem. I have no idea how far I am from the nearest cabinet is (I'm in Epsom, Auckland) and to be honest I don't know what a cabinet looks like - how do I find out, is there some online map of cabinets by area? I have seen the http://bcc.telecomwholesale.co.nz/# site, which says my cabinet is MOD/W, but it doesn't seem to show the exact location.
The modem is a TP-Link TD-8840. Stats as below:
Mode: ADSL2+
Line Coding: Trellis On
Status: No Defect
Link Power State: L0
Downstream Upstream
SNR Margin (dB): 6.5 14.2
Attenuation (dB): 43.0 23.3
Output Power (dBm): 0.0 12.9
Attainable Rate (Kbps): 2768 1200
Rate (Kbps): 2212 1020
MSGc (number of bytes in overhead channel message): 54 10
B (number of bytes in Mux Data Frame): 14 145
M (number of Mux Data Frames in FEC Data Frame): 16 1
T (Mux Data Frames over sync bytes): 5 1
R (number of check bytes in FEC Data Frame): 10 0
S (ratio of FEC over PMD Data Frame length): 3.4247 4.5447
L (number of bits in PMD Data Frame): 584 257
D (interleaver depth): 16 1
Delay (msec): 13 1
Super Frames: 1901521 1901519
Super Frame Errors: 0 0
RS Words: 35653534 0
RS Correctable Errors: 436 0
RS Uncorrectable Errors: 0 N/A
HEC Errors: 0 0
OCD Errors: 0 0
LCD Errors: 0 0
Total Cells: 159297981 1871616
Data Cells: 25889797 3893
Bit Errors: 0 0
Total ES: 48 0
Total SES: 13 0
Total UAS: 5565 0
Appreciate your input on this.