I was an SSE customer but with the take over my account has been migrated over to OVO.

The first month i did’nt really check what was happening with my  OVO balance as im on a smart  meter.  at the start of august i checked my balance against my bill ,my ending balance was  £126 .a few weeks later i was checking my usage and saw that my balance had gone down to £116 check if i had been billed again ? no ! checked if there was any information as to why it had gone down , again no! so i called OVO and asked why my balance had gone down before my billing date and what the charge was for i was giving a number for SSE i was been charge by them and they where debiting my OVO balance , so i called and was told that had no idea about it and that my SSE account was closed and migrated over to OVO  i so  i asked for them to send me  an email stating so with closing balance ,they did so . called OVO back and asked again why my balance had gone down  before my billing date  this time i was told they had no idea why my balance had gone down and was told that it would be passed to complaints department. ok!  i checked my balance 2 days ago it had drop again to £108  and today again to £107 so far it has drop by £19 pound,So  to day i call to find out what was happening with my compalint only to be told that complaints had no record of my issue again iwas told that i would be passed to complaints and that i would be contacted in 5 working day at this point i got in contact with citizens advice and was told to send an email of complaint so i have a copy and  that way there was proof that i had been in contact      .been the person  that i am( terrible memory )i always record my phone calls  when it comes to  bills ,debts and anything to do with money and keep all documents. so just to let you if your losing money from your balance without reason or been informed as to why you not the only one  and im sure there are alot you out there  paying more than you should be keep and collect all evidence