update 3: when we got gone after our experience in Leeds we rang apple support and expressed our dismay, whoever we got at the other end of the phone was a godsend. We expressed our rights under consumer laws, (1 year warranty plus 2nd year courtesy fix) he contacted Leeds who in return gave two flimsy responses:
1) our original complaint was noted down as a a microphone issue hence not a speaker issue despite us insisting it was a speaker issue.
2) in their repair they did NOT leave the new speakers in as they did not fix the issue (this contradicts their stance in store where they stated they left the new speakers in)
to is it seemed like Leeds were trying to change the goal posts. The support rep said he would take a return and try another repair or replace the handset free off charge.
we agreed to this.
they repaired the phone and sent it back. It’s all working. So we asked what was the issue? He was vague: “it was moisture damage to a component”
we said: but it’s waterproof? Which component?
he couldn’t tell us.
so in summary: it’s now fixed, we don’t know what they did, it wasn’t what they’re saying (moisture damage because it’s waterproof), and the store in Leeds were simply unhelpful and in fact went out of their way to be unhelpful.