Long debate I had with someone over this issue. The fuel pump is internally, not externally cooled. The external cooling would account for at best 5%-10% of its cooling capacity. Instead, it relies on the fuel being sucked in to cool it as many pumps do.On a more serious note, never let my tank drop below a quarter, dang fuel pump needs to be submersed in fuel to cool it. Otherwise it runs red hot and doesn't last as long.
A dismantling of said fuel pump would show that the outer casing is not in any consequential degree in contact with any of the internal parts, let alone the ones that need cooling.
But I digress. As I've recommended to everyone who has a problem here, contact GM first and have them deal with the dealership on your behalf. If you can, get a video of this behavior to prove it. This will allow GM to intervene on your behalf so you don't have to, and if necessary, find you a more competent dealer to service your car. This also reports your problem so that should anyone else also have the problem, it will be another hash mark on the priority list for the engineers to investigate and hopefully release a service bulletin for.