Ampy electricity meter cards

Once again i am asking a question to you guys , you answers so far have been so helpful!

We have an Ampy card electricity card meter which we were advised to have installed to help with guest renters using too much electricity per rental.

The lady who previously helped us with cleaning etc used to get us cards but I can't get hold of her. Does anyone know how I get them?? I can only find them in £££ on the internet.

Once again thanks for all your help

Alison