Problems with Proline LD2215D Digital TV?

I purchased a Proline 22 Digital TV model no LD2215D.
I am getting a poor digital reception. I have 3 other digital TV‘s in the house and all work perfectly, plus a freeview box set up. I have tried the TV in all the other points in the house but still no picture.

I returned the unit to the shop where purchases. They got the TV to work on there setup obviously a highly boost network system considering the number of TV’s working on the system.
I tried again at home
I get the blue information bar up which show the Chanel but no picture and it shows a signal strength of about 3/.4’s of the way on the bar.

I have since tried the TV at my daughter house – She has a new digital Arial – still I could only obtain about 2/3 or the channels only.

The analogue system works perfectly in all the locations.

It appears that this TV must need a very high digital signal – If this is so should there not be a warning on purchase.

The store say they can’t help me as because the TV works in store on there system.

So I have just spent £249.00 on a useless TV and might as well put it in the dustbin.

Anything you can suggest would be appreciated.

Rgds
Ian