Here's what I know:
The ATR has been grounded since December due to maintenance and "upgrades". No news on when its coming back.
The 737-300 "Kwacha" is stored in Johannesburg because QM can't pay the maintenance fees.
The 737-500 is also stored in Johannesburg, missing one engine. No money to pay for a new one.
Instead, QM have dry leased a 737-200 from Mozambique for 1 year in full QM colours and with Malawian reg. Allegiance air have been flying their EMB120 on contract for the past 5-6 months, but have apparently just pulled out. This means that QM are down to just the 732. They have started codesharing with Zambezi on flights to Lusaka and Dar.
Hope this helps