Not impressed with Bulb's communication or rather lack of it

I have moved over from my previous supplier who only supplied prepay electric. We went over to a key meter years ago by choice but want to move back to a credit meter as the tariff is much cheaper. I’ve now moved to bulb where I was told I could have a credit meter but first step was to transfer to them with my prepay account. I’ve now been told that I haven’t passed the credit check despite having no debts except a small mortgage which has never been in arrears. Although I have questioned this by email I have had no substantial answer and my final email has not been answered. I’m not impressed with the service and am now looking to transfer to another supplier who is able to sort this out. I’m just wondering if this is standard behavior for this company. Many thanks, Michael