Bad service

I've been trying to get my one contract's billing sorted since the beginning of 2015, 7/8 months later query is not sorted, several emails sent, a recon need to be done as from the date 1st payment was made as I've been billed incorrectly in some months<br> I upgraded my handset on my other contract, sent the insurance update form more than a month ago, details are not updated, now I have a handset that I don't use as I need to have my insurance updated prior to using it