Dimplex Quantum storage heaters- Expensive to run?

I have 4 Dimplex Quantum storage heaters in my rented local authority 2 bed end terraced house. Gas was removed in favour of these supposedly greener and more efficient heaters. Truth is they are way too expensive to run. My home is small and thankfully well insulated. However, if I were to run all four, I’d be roughly £600 per month…Yes, Per Month. So, I only have the one in the kitchen on as it’s a tiny kitchen and the heat from that keeps my living room ticking over. I bought two electric panel heaters, one for my living room and one at the bottom of the stairs. The latter heats all the way upstairs. They are far easier to control, whereas the storage heaters are useless. No heater in the bathroom, so I have a low energy electric towel rail which is pennies to run. But, depending on how long I have the panel heaters on, I can easily run to £14 per day. I’ve tried it when we have really cold days. I was told that the storage heaters need to run on economy 10, which they are. But, then I was told they should be on economy 7. Does anyone out there have these heaters? What are the costs for you to run them? They are not like the old style bulky storage heaters of the 70’s they are quite stylish, but so expensive. I’d love to know how they are supposed to be economical. When I had gas it was far far cheaper to heat my home. My neighbour still has gas as they bought their house, exact same as mine, their gas for heating and cooking is £125 per month. Their electric £40 per month. Their are four people there. Here there’s just two of us.