Franke Monobloc Tap Won't Switch Off

[paulbanco]

I am the not so very proud owner of a rather expensive Franke Monobloc Mixer Tap which won't switch off the hot water.

The tap itself has a substantial solid stainless steel base mounted on the kitchen worksurface, gooseneck spout comes out the top and two barrels enter into the side of the base each with a screwed in lever that points vertical in the off position and moves 90degrees towards you to full on position.

The hot tap has stopped working and is stuck fully open, move the lever up and down but nothing happens.

Anyone know of an obvious answer?

 

[muggles]

Something's come apart inside, if it's under warranty get Franke out to it