After renewing contract nothing but billing issues.

Hi All,

I recently renewed my contract with virgin media since then I have had to contact customer service several times to resolve billing issues. 

I agreed to renew my contract which is supposedly £42 per month but according to the virgin media app my bill is £47 per month, I was given a £5 rolling credit for the length of the contract. Each time I contact customer service via the web chat they assure me that the issue is resolved and it not happen again, yet viewing my bill it still does not show the rolling credit, any credit that gets apply then comes back the next month saying I didn't pay the correct amount, something is messed up within the billing and customer services systems which is causing me this headache. Can someone please help to resolve this once and all.....

Regards