shareholder tax query

TOOMUCHWORRY

A relative was offered a permanent job with a company that they had done work for previously as a self employed contractor. He terminated his self employed status assuming he was now paye.
He was told that a certain fixed sum would be paid into his bank account each month and the company would deal with the tax and NI.
Relative kept asking for payslips at end of month and also asked about having a contract. Employer kept saying oh I'll sort that out but never did.
6 months later the company told relative that job was finished but they would pay him until end of month.
When relative asked for P45 he was told that he had been paid as a share holder. Relative is sick with worry that his tax and NI are up to date as employer insisted it was.
Previous employer is now not returning calls after being asked for written confirmation on what tax has been paid.
Sorry if this is confusing - we are totally confused by this too.
If anyone has any advice we would be grateful