Plaster falling off!

[rara]

Hello all
Can anyone advise me a plastering problem, I had my house plastered 5 years ago, now its falling off in sheets!!. Theres one coat (called the scratch coat i think) thats pretty well stuck to the 1920s brickwork its the 2nd coat of sand/cement/lime thats come away. Im wondering which plaster i should use. -cant get hold of the plasterer.
Thanks in advance for you help

 

[Alastairreid]

Is it the external render you are talking about?

 

[rara]

Is it the external render you are talking about?

thanks for the reply. Its internal, bedrooms and living rooms.