C4 Grand Picasso Front Seats

[Mobos17]

I have a Citroen C4 Grand Picasso with manual front seats.
Recently I noticed that both my front seats are fixed in place and will not move in either direction. I have cleaned out the runners as much as possible as well as greasing them.
My local garage has had it in for a week and have been unable to find what is causing this. There is an added issue that the seats are fixed over the bolts attaching them to the car, so I am unable to remove them to look at the runners clearly.
Does anyone know if there is a secret switch/fuse/method that i am unaware of that I can look at before I have to resort to ripping them out and replacing them.

I am not sure if it is related but I also have a leak coming through into the drivers footwell, this has taken out my heating and aircon and I am getting this sorted soon. However I am wondering if it may have effected the seats?
Thanks

[PaulC5]

Leaks are common on this car, as an example topic viewtopic.php?t=81424

[Richard_C]

I would check that the release lever is working properly. It's a bit odd in the Picasso, not central but an L shaped handle on the inboard side under the seat so I assume it pivots somehow. If you adjust the height upwards you should be able to see if it's un latching. Mines gone now but I never had a seat problem in 8 years.