The tailgate on my 05 estate has got increasingly difficult to open. I can hear it operating when I press the button but it doesn't release very often. The car has no manual release lever down on the sill. Any ideas what the problem is?

Try greasing the mechanism and the latch bar.

mine does the same, a little push down whilst operating it usually releases it first time.

I'm yet to grease it up though!

ok thanks I'll take a look and grease it up a bit.

I use aerosol white grease when servicing my car for all hinges,locks, wiper arms, bonnet and tailgate release mechanisms.