I am not a solicitor to give you the most appropriate answer. However, what I understand from your statement, normally the builder is supposed to supply all the utilities in accordance with the local authorities. In practice the partner builders or some abusive actions may cause uncomfortability to the buyers. First of all the utility debt of the builder and your household should be different.

It would be better to consult a nearby solicitor in order to compensate your cost and force the builder/electricity company to correct the issue....

regards