It's a very simple procedure to DIY, unless you're really unsure in which case leave brakes to the professionals.

It's most likely the sliders.

In which case it's just a matter of jacking up the car, removing the wheel, then it's just the 2 bolts on the ends of the sliders

(the ones you have to remove to change brake pads)

- once removed just re-grease with a suitable lubricant

(I use a high temperature LM grease).

If it's sticking pistons then personally I'd go with refurbished calipers.

Toyota sell a seal kit which is around

£50 per axle, and the pistons are around

£10 each.
