I’ve only had a pay as you go account and that was over 4 years ago at a previous address so I’m not sure where they’ve got this from?

Hello, I’m looking for some advice with regards to some dodgy looking letters Ive received from Lowell. They have sent two letters to my parents house (long story but using this as a c/o address until I find myself a new home). They sent two separate letters, one with their standard give us your money with a letter of assignment purportedly from Vodafone in one envelope then another separate give us your money with a letter of assignment from everyday loans. It’s not so much that I’ve never had a Vodafone account and the amount being claimed by everyday is nowhere near what I did owe some years ago, it’s the very dodgy looking letters supposedly from Vodafone and everyday assigning the debt to Lowell. Both are on the same paper, with the same font, with the same data matrix codes as the Lowell letters, both with the same numbering on the edges of the letters, both with badly scanned images of the company logos. I’m going to send them a prove it letter, pointing out the highly suspicious nature of their letters of assignment. Aside from this any suggestions on what to do with these dodgy looking letters of assignment? (I would upload but not sure how to on here?) Thanks