Fitted the new battery today. Before I did I thought I'd weigh it and compare to the 65ah one. The new battery is 1.45kg heavier than the 65ah one. I was expecting more to be honest.
Yes it's a shame you don't know what was said but I would imagine the techie gave them the distinct impression the previous job was to blame to manage an 80% discount. I doubt they will ever admit full liability though
That doesn't seem too bad on balance as it would be hard to absolutely prove what caused it, despite all of us having a good idea what did!
You will get 12 months warranty on it, so if there are further problems you'll at least be well covered.