HMRC has started rejecting my CIS returns. I have manually submitted last two. My payroll submits okay, and the user details and password are correct. How do I fix issue

HMRC has started rejecting my CIS returns. I have had to manually submitted last two. My payroll submits okay, and the user details and password are correct. How do I fix issue? Also, for past six months or so, I have not been able to submit my pension to Nest. I have tried resolving issue with QB and Nest and still cannot submit and have message I have to manually submit each week when submitting my payroll. Really not impressed with QB never had any issues submitting my submission with my last payroll software provider.