Just received my 2018 AMG C63 s Cabriolet, also had Mercedes order me their Custom Fit (?????) AMG car cover, it does not fit the seam on one side started to separate as soon as we tried it on. Tried a second cover when you get the cover under the rear spoiler it lifts on the front and vice versa. Part number 205-899-03-86. Any suggestions for an alternative?