As previously stated, you should receive an Electrical Installation Certificate (EIC) for this work. You will need to find out whether the installer is registered with a government approved scheme (such as Napit, Elecsa or NICEIC, there are others) or is suitably qualified to carry out such work. This is because the work has to be notified with the local building control (LBC). Notification is done automatically through one of the schemes, or if not the installer my have some process with LBC. I'm in a scheme, so can't comment on the latter. An EIC and notification can take up to 30 days to come through. I think it would be best to make contact with the installer enquiring about the EIC & notification to the LBC. In terms of what was paid, did your mother receive a quotation/estimate for the work? Did it state anything about certification or notification. Certification is required on completion of the work, but notification can be the responsibility of the householder.