Hot air blowing into the car is a symptom of the dead control unit - all flaps and settings defaults to HOT -- probably because the winters are so cold (other than here and Australia ...) that cold air is not a good default setting for sub zero temperatures.
anyway, fuse 7 (on my W124) powers the control unit - check the fuse out again ...
could be that the control unit popped because of the faulty alarm unit - who knows what wires were used for powering the alarm system ... is it an OEM alarm or aftermarket ? OEM will be within MBSA's scope to fix ...
So far it does not look too good - control unit is probably shot and it's quite expensive from MB. Try Majestic in downtown Johannesburg for a used unit ...
BTW, the hot centre console is 'normal' considering the ample amount of heated air, combined with 25+ outside temperature, entering the car .... shut off the fan, close the vents let the air flow via the defrost vents - a bit more bearable. Be glad your not in Messina !!!
BTW 2 Does the aux fan work with the air con on and the engine temp above 100deg C ? If it doesn't, you probably have a power related problem from fuse 7 downstream.