How can I report a missing interest reward on my account if eligible and not receiving?

I have been a customer of OVO for more than 4 years.

OVO openly offers 3% to 5% on customer accounts in credit during each year.

I have not received any such credit over any period with OVO.

I have always been on a fixed price contract, and on smart meters with this company, and as the contract starts on the 1st April I acrue significant sums over the summer period.

With massive increases in energy costs, the sums  that will build in the summer time, on a fixed price contract will be particularly large, making the interest payments offered (if they exist) extensive

I have made at least 5 attempts both now and in the past to persuade  OVO to explain why the publicly trumpeted credit system does not apply to my account. This simple question has been fobbed off or told it will be passed to another department in phone calls , emails are totaly ignored and even a personal letter to the General Manager has produced no response.

As this company was fined a very significant sum in the recent passed for over/undercharging customers and refuses to communicate with it’s members I begin to wonder what I’m doing taking out annual contracts with them.

Has any other member had similar problems? If so please advise. Maybe I’m in error thinking this credit sytem applies to me, or maybe filled in the wrong form etc.

Any advice from members would be appreciated

Tony Purcell