wez_1,
Your issue sounds very much like local wireless interference, you may want to read these two
(hopefully useful) links:
Reducing Wireless Interference
Local Network Stability
If you cannot get things working correctly by following the advice in those links, you could also
Submit a Sonos System Diagnostic for further investigation and then choose to contact Sonos Customer Care directly, using this link below:
Contact Sonos Customer Care/Twitter (24/7) etc.
Anyhow I truly hope that helps and that you get your 'likely' local wireless network issues resolved soon.?