I was dealing with them during covid. Unlike Scottish Power (who just seemed to close up shop and turned the lights off as they went), they'd transferred their customer service to Bosnia. I spoke to several agents all of whom spoke very good to excellent English, and seemed to know what they were doing.
Their prices are excellent, and the only energy company I know who have sent me an email after I joined to say they've cut the prices I'd already agreed to!
Thus far excellent.