You need to check the cost of what you use each year and whether it matches your DD (the £850 of arrears suggests not). Your bill should tell you how many units you use.
There are special EV tariffs, which might not push your day rate up as much as Eco 7. Unless your utility tariff is very cheap, you'll probably be better off with another supplier, £100 for broadband and phone is very expensive - UW has always seemed like a bit of a con to me - you can save on G&E but only if you pay over the odds for the other bundled services.
The other thing to check is that they're billing you in the right units for gas - sometimes there's a mistake which means you're billed for about 3x more than you're using.
But if you are using that much, you should also look at whether you can reduce your usage as it's huge, I thought electric cars were supposed to save people money, so there must be other reasons why your bill is so high - google energy saving advice and look at reducing your heating, hot water, washing and drying and cooking costs, this is where there will be scope to cut down.
We're with Octopus, who are pretty good and have an EV tariff. If you sign up using my referral link, we both get £50 account credit:
https://share.octopus.energy/loved-moon-894