AndreaICF

Not sure if this is the right place to put this but here goes. I have a SIPS panel roof with a membrane. Battened and counter battened with 25mm yellow battens. The roofer said he would use copper clouts on the slates but has actually used aluminium nails. The warranty provider inspected the roof at the time and said it was acceptable. The next inspector has indicated that he will not warranty the roof with aluminium nails in. I paid for copper nails so I am very disappointed that they weren't used. Am I going to have an issue in the long term with the fact that they used the wrong nails? I wanted a slate roof so that i didn't get a build up of moss and I understand (now) that it is the properties of the copper nails. Any comments.