Just a heads up regarding the Spark Apple Watch Wearable Plan and what happens when you switch to a new watch - you could end up with multiple plans on your account.  The case scenario for me was:

1.  My wife broke her Apple Watch Series 4 that had a Spark wearable plan attached and we ordered a new Apple Watch Series 5. 

2.  On the broken watch we disconnected the Spark wearable plan and factory reset the watch so we could send it to Apple for repair (whole different story of woe 😬).

3.  When the new Series 5 watch arrived we set it up and set up the Spark plan again on the watch/iPhone.  All good so far.

4.  At no time during the setup did it say that I was signing up to a new plan - I assumed, naively, since I had disconnected the plan on the old watch the setup on the new watch would connect to the existing plan.

5.  Have just received my Spark bill for the month and have two charges for wearable plan for the last month.

6.  Spark sorted the issue with no fuss, however had I not been paying attention I could have gone months without realising.

@Spark, i suggest that you put in place some procedures around this as with a new Apple Watch likely in the next few months, I'm sure there will be people disconnecting their old watches and connecting their new ones without realising they have signed up to a completely new plan.