Green Star Energy

I received a renewal notice as my existing contract is ending 6/2/17, offering me a choice of renewal tariffs. I replied by email with my option Ratesaver fixed 12M- 1612. No response. I then tried using the online form. No response. I emailed again and received an auto reply saying response within 5 working days. No response. I called customer services and explained my problem to be told that the tariff I had opted for was no longer available although it is still on the comparison sites. and was valid when I first emailed. I was offered a similar tariff Ratesaver fixed 12M - 1701 which I accepted, and asked the agent to email the details. Still no response. I now have a letter informing me that I am now being put on that tariff but the direct debit amount would be £80, the same as previous despite the estimate of £67 by the agent. There is a surplus of £555 on my present account which is subject to the final bill from the present contract. Will the excess be refunded to my bank account? Is there a fundamental problem with this company's customer service? Kind regards J C McEwan