Hi,
A single coil insulated cylinder, (30 gallon, 18" x 30") is approx e145,
I assume they'll supply and fit a new immersion, e40,
60 gallon tanks are standard so it should be similar in size to exsiting tank, cost approx e60,
Tank connecters, ball cock, pipe, cylinder connections approx e100'
These materials will have between 10 to 25 precent mark up(to cover transportation cost, pick up etc)
You can expect to pay a decent plumber upwards from e250 a day depending on location and availibilty.
And don't forget the VAT.
You do the math, hope it helps!