Hi, I am having this same issue. My gas meter reported a battery fault and an engineer came out and replaced my gas meter and now I'm being charged the higher rate for the first 61kwh instead of the first 2kwh.
I have called customer services 6 times to be told that my meter is set to the correct tariff and nothing can be done. If I use my gas I'm being charged over £10 a day for 6 hours of heating and gas use when my costs before the meter change were around £2.00 a day.
The customer service has been shocking and nobody at Utilita will listen to what I'm saying and just tell me what their computer screen shows. One representative even put the phone down on me as she was getting flustered.
I will be complaining to Utilita and Ofgem and I'm still waiting for a refund from when this started on November 22nd so I'm already owed around £80 which I doubt will be refunded.