Refer a friend credit not used

Hi,I joined Bulb on 29th July with link from a friend. I got the £50 credit but for my first month Bulb took payment from my bank account. I phoned to ask why the money were taken from my bank not from the credit and a staff member explained me that I will be refunded. I am still not refunded and also yesterday Bulb took money from my bank account again for electricity for September. What’s more,not only Bulb keep taking money from my bank account and not using the £50 credit from “refer a friend” but also there is some mysterious payment that Bulb have taken for £38 from those £50 which I can not understand for what is as I switched to Bulb on 29th July and Bulb took money from my bank account for August and September already.