Entroga Direct Debit Payments

Has anyone had problems with Enstroga payment system. I increased my direct debit in January 2019 and asked the customer service advisor if it was enough, who said let it run and see. I monitor the monthly meter reading and charges and could see that it was not enough, but by the end of contract would have closed the gap. So I wanted to increase the direct debit as I had a large debit balance, built up during the Winter. Enstroga appear to have changed their policy switching to quarterly billing and now want the debit balance paid over two months and my normal direct debit payment. This would leave me massively overpaid by end of contract. Surely this is not on especially where people are struggling to pay utility bills. In my case this would more then double my monthly charge for two months and then at the end of contract I will have well overpaid!