Miway overcharged me

I am so disappointed with Miway.The kind of treatment I am getting yet I have been a loyal payer.I was charged more than my normal installment last month(June).I reached out to them and they said to me they would refund the money back into my account in 7 days.7 days is over and there is still no such in my account.This is a huge inconvenience as the overcharged amount was supposed to pay for another debit order.Now I have tried to get a response from them and I am getting none.