I bought building material for renovating my mom's house

I bought building material for renovating my mom's house. Amongst these were corrugated iron for roofing- 4.8m IBR. I think the supplier to Cashbuild for this 4.8m IBR,is Mac roofing, because Cashbuild shared my complaint with them. The problem with the 4.8m IBR is that it started rusting very badly in a very short space of time. I am raising my concern here, because Cashbuild simply ignored my complaint after forwarding it to Mac roofing. A roof is something that should last for year. It is therefore very concerning that it should be rusting in such a short space of time.