Hi folks. Looking for some general advice thanks.

Bathroom renovated in 2015. New tiled double shower installed in Christchurch. Concrete pad. Proper framing and gib etc.  Waterproofed. PS3 producer statement issued at end and lodged with council etc.   

I've just finished decorating a bedroom today and noticed some swelling on the mdf skirting. It's the same wall that backs onto the shower/ bathroom. Fearing the worst but hoping for the best I pulled the skirting and it's definitely wet with some black mould so been leaking for a few weeks i suspect. 

It backs onto the long wall of the shower and the plumbing and fixtures are on the side/ short ends so pretty sure it's the waterproofing that has failed and not leaking from the mixer etc.

I've informed the insurance company but have a feeling after reading the policy this is gonna be on us to pay 95% +. They seem to have a token amount for 'slow leaks'. I will check with them re cover next week. 

Did some googling - builder has gone bust in 2017, plumbing company that did the waterproofing went bust in 2019.

The product used was MCB Aqua Block which i see is a SIKA product.  Do you know if they guarantee the membrane at all if installed by an approved supplier given it failed just over 6 years since install ?

I also see some companies using epoxy grout to also undertake repairs of failed showers - meaning no tear out but have no experience of this type of product.

Have also priced a refit of the shower at between $10K and $12K based on rough estimates - gib, tiles, waterproofing, labour etc - that's using existing showerheads etc as well.  Am if miles off ? 

Cheers 

Ged