One of my front parking sensors (nearest number plate) was accidentally pushed into the bumper so I contacted the local dealership for a quote to relocate it. I was told it required a full bumper disassembly and I was looking at between £250-£300.

Having recovered from the shock, I decided to give it some thought and fixed it myself using the following:

large flat head bolt slightly smaller than the sensor face
no more nails double sided contact adhesive tape.
surgical spirit.

Clean the bolt head with surgical spirit and apply a similar size piece of the contact adhesive tape to it; trimming if necessary (see pic). Try and clean the face of the sensor inside the bumper. Remove protective film from adhesive tape on face of bolt and feed it through the bumper hole and stick onto face of sensor - leave it for a few seconds to grab then pull steadily, rotating if necessary until the sensor locates back into its housing. Apply a couple of spots of super glue around the edges to secure. Job done and working perfectly!

Great response and solution!

Superb idea!
I took the blooming bumper off to push it back and superglue the behind