Hi Bambo,
Yes in order you to have a situation whereby you are given loan offers for the purchase of the new property while the old property is not yet sold, is referred to as "closed bridging". In this situation the bank will insist on contracts on tha sale of your own property being signed before issuing loan offers fr the purchase of the new property.
In our experience the only banks that offer this are the banks that hold the origional mortgage.
Your bank should have let you know about this and I would not be surprised if this was the reason that the decline came back, as a bank would not normally loose a customer over a €15K difference (i.e. diff between €270K and €285K).
Hope this helps.