Meter readings gone up & down

Hi
I’m trying to sort my payments out but I have a problem in that my meter readings are all over the place. Since October they’ve gone up, then down, then up and down again…not just on customer readings but also on the smart meter reading taken by Bulb. My account says I’m £549 in credit but this is because the meter readings are messed up. Ive contacted Bulb but they say the meter readings aren’t often wrong and if I have an engineer come to visit and the meter is not inaccurate, they will charge me £149 or similar. I wouldn’t commit to that because I don’t know whether it is the meter itself or something else. How can I sort this mess out? Any ideas gratefully received :slight_smile: