Jammed heater control

[pinna]

Hi, I've just joined this club as I'm curious to know if any other Galaxy owners have experienced this problem. Car - 2008 Edge diesel automatic ex-taxi, bought 5.5 years ago at 93,000 miles, currently 155,000. Few problems to date, apart from a series of poor quality motor-factor starter motors (won't make that mistake again!). BUT...........always had a rather sticky heater/ventilation direction dial (the one on the right in the row of three) which has now virtually seized. You can turn it just when the engine is stone cold but within 5 minutes of engine running, it's virtually impossible to alter. Local Ford dealer tells me it'a £1500 repair, involving £620 worth of parts, plus 7 hours labour plus VAT.  I'm curious to know if this is an   unusual problem as it rather puts me off buying a second newer Galaxy and if anyone has any suggestions as to what alternative course of action might at least alleviate, if not completely cure, the problem.