Not Locking, Mad Electrics, Crazy Avensis, Driving Me Crazy...

[jatwap]

..ok, just another in what appears to be a large number of crazy "won't lock", "mad electrics", "wonky avensis" style threads! :P

My car is T reg 1999 Avensis GS with symptoms being:

• Car won't lock using keyfob though lights do flash twice to suggest car is locked (it does lock via key in door and does unlock using keyfob)
  

...has been like this for over a month (applied workaround of manual locking ever since frustrated attempts to fault find last time round!)

Now, today the following issues:

• Rear demister stopped working and
  
• Heating not working anymore (cold air pumping out constantly)
  

Any suggestions?...(have checked fuses, all ok. Door locking mechanism all work ok from inside car.)

What would you suggest I try next? Heating top priority, then locking, then demister!