Joao Cabrita ...
I had several collapsed cakes in my low cake decorating experience but everytime that happens i ont go down and i learn with mistakes.
I think that you shouldnt keep the cakes in the fridge, when they came out the sugarpaste/fondant starts to melt.
Also i think that primacakesplus is right when she says that the support of the dowels could be not enough fot the cake you made.
Next time put some good dowels to support all the cake, make an “inside view” on how the cake could be supported so nothing go wrong.