This answer applies to R4 Mk3
Depending on usage, it may be that the coin cell battery in the remote is coming to the end of its useable life and needs replacing. The battery type is CR2032 and these are available from many retail outlets. Also please check that the negative battery contact inside the remote control is raised so it makes good contact with the battery. If it has been squashed flat raise up slightly with a small screwdriver or suchlike.
Secondly, if you are using your R4 near artificial lighting (particularly low energy types), then please try turning these off and check the remote function again. From experience we’ve found that some low energy lights emit interference which affects the control system resulting in unresponsive or erratic behaviour.
If not, please do not hesitate to contact us directly on +44 (0)1702 601410 or by using the enquiry form on our contact page.