Rear Parking Sensors - how to access?

[Funkmachine]

So my parking sensors have a fault, which the OBD says is due to the rear, RH inner sensor not working - question is, can anyone tell me how to access the sensors. Ideally I'd like to clean up all the connectors using contact cleaners to make sure the connections are all good in case its something like that, rather than an actual sensor failure - if that doesn't work, clearly I'll need to get a replacement sensor from somewhere (has anyone on here found a reliable source, other than peugeot main dealers).

I've seen the YouTube video on how to remove the rear bumper, but its a major operation and I'd rather not do that if i can avoid it !!

Thanks very much for any help and suggestions