I spoke to a Apple Support Advisor last night and he also advised me to do the 90 minute DND trick but I calmly explained I've done that to no avail.
He then checked that I had updated to iOS 7.0.2 which I have and then said it is a hardware fault and I've done all the required checks.
He said my handset needs to be replaced and as I'm within my 14 days I can take it back to the store I bought it from and get it swapped out for a completely new handset.
I did add that I've seen people swap them out for new handsets but to no avail and he said I am the first person he's spoken to to call up about this issue and it would be VERY unlikely my second handset would suffer from this issue.
Given the uncertainty of it I think I may just return the handset and then see what comes out of it with the software update.
He then checked that I had updated to iOS 7.0.2 which I have and then said it is a hardware fault and I've done all the required checks.
He said my handset needs to be replaced and as I'm within my 14 days I can take it back to the store I bought it from and get it swapped out for a completely new handset.
I did add that I've seen people swap them out for new handsets but to no avail and he said I am the first person he's spoken to to call up about this issue and it would be VERY unlikely my second handset would suffer from this issue.
Given the uncertainty of it I think I may just return the handset and then see what comes out of it with the software update.