Dear Stefano,
Before you send anything to Olis I think you have to check exactly where problems come from.
1. In year 2014, we installed these units for you. Problems with damaged control boards for all units came from your unstable electricity. This, your engineer knew about it and fixed it after we told them to. Reason for this is because you use 3 phase electricity and your engineer has to install the phase protection inside the MDB. In fact, if problem does not come from MANUFACTURING DEFECTS, OLIS CANNOT CLAIM FOR YOU. However, we managed to get them to claim for you since you bought a lot from us.
2. Year 2015, we don’t recall you have any problem.
I really don’t know what is the situation for this year symptom. Should you want to know what exactly could be the cause, it would be quite difficult unless we check your electricity and other activities that have been happening in the past months.
I will check with my purchase on how long would we get the parts shipped to us.