Debt

Hi, after spending months contacting virgin due to my bill being doubled every month for over 5 months. I was informed by a member of their team to raise this issue with my bank as they could see no record of the transaction. Which I did, several months down the line I’m now being contacted by some debt agency called advantis saying I owe hundreds. I’ve tried multiple times getting through to virgin and all I’ve been getting is I didn’t pass the security checks because for some reason I can no longer gain access to my account or even login into my account anymore.

any help would be appreciated 

absolutely shocking customer support.