Unless the points are coming from MS or a trusted retailer, I'd suggest staying away from them. If another company is offering to give MS points away as a promotional item, that's fine, but MS is not responsible for you being given invalid or used codes.
Did this solve your problem?
Sorry this didn't help.
Great! Thanks for marking this as the answer.
How satisfied are you with this reply?
Thanks for your feedback, it helps us improve the site.