Hi Vin, i reckon its possible that after you left the job and the surface had dried out, your customer saw some water spotting which would show up well on that colour door, probably went looking in the cupboard under her sink picked up some cleaner with caustic or corrosive ingredients and proceeded to spray it on the door as you can clearly see the run marks/etch marks as the chemical will have run down the door, most cleaning professionals will know from experience that you should always when using a chemical cleaner spray a vertical surface from the bottom and work up to the top, as this will stop the chemical causing run marks on the surface, again i would ask your customer did she spray any chemical cleaner on the door surface after you left, it shows all the evidence of chemical etch marks running down the door and your average householder would have no idea about always spraying chemical cleaners from the bottom up on a vertical surface to stop these run marks, if it helps you out Vin we do carry an aircraft quality wax which would be far more effective than the Autoglym one you tried, it really depends how deep the etch marks are gone into the substrate, if you want to give it a go send me your Shipping address to
info@jskcleaning.ie and i will send you over a bottle to see if it might rectify the problem.
Regards Tadgh