If you have paid for a report, they should not be withholding it.
After all, you asked them to do a report, not give you a list of things you must do before they will give you a report.
Write them an email, along the lines of.
I have ordered and paid for an EICR to be done at 123 any avenue.
I have now waited x days for it and find this unacceptable.
please provide the report as ordered as soon as possible and in any case within 5 days or i will seek advice on how to recover the money paid to you for a service i have not received.