Your parents are over 50 years old, and the longest loan period is about 10 year. Generally, 65 minus the current age is the longest loan period. But if the company is good or the credit is good, you can apply for a five-year extension.

In addition, in order to reduce the requirements for banks, I suggest that you pay more if you can, and try to reduce loans so that banks can easily pass the audit, otherwise it may not be easy to get loans.

I don't know why you can't get a loan. I suggest you go to the sales office to consult the sales staff and see if there is a better way.

For reference only, I hope it helps.