A couple of years ago one of my customers took down an ivy from a 2.5m x 8m upvc facia. The whole thing was green, and covered in the little suckers. At the time I said that I would do my best, but didn't want to go mad on it in case I damaged the upvc. Initial result was good, but the little sucker marks were still there. The following (annual) clean was much easier and the sucker marks all came away easily with wfp and tap water.
Facia is now good as new and punter is happy, and understood that some things take a bit of time and patience.