I get my pay slip in pdf format with company logo, name and address. My previous company HR is saying they wont sign or stamp any letter for old employees.

Now i have manage to get my manager to sign and put a seal on my pay slip and issue a letter saying the pay slip is issued in the form Last name + First Name.
My doubt is is a manager's signature valid or do i need to try with the HR manager's sign ??

Please help.
Regards,
Joe