Not to be rude inasoup but I think you need to learn a little about loans and interest before taking out a mortgage! If you are finding this loan difficult to manage you will find a mortgage even more so.
As Bronte pointed out you have NOT repaid the €18000 borrowed. You have repaid some of the €18000 and some of the interest. The remainder is still outstanding. The same would apply to a mortgage, just because I have paid in say €10000 this year does not mean I have paid €10000 off the capital balance. A sizeable proportion of that payment is interest. In short, by next month you will NOT have repaid the €18000. You need to disabuse yourself of that notion right now.
1) You can always ask but I suspect the bank will not reduce the interest charge. You appear to still be able to afford the repayments and have been making them so there is no reason for the bank to be generous to you.
2) If you were looking to consolidate this debt into a mortgage debt you would have to have a reasonably low LTV (loan to value) ratio for the property, in other words not on a 92% mortgage. I am assuming if you are looking for a mortgage you probably are buying a house for the first time? So you don't currently own a property to use as collateral on such a mortgage. Northern Rock in the UK a few years back did mortgages like this - look at what happened there! Furthermore you would also have to check if there are any break-out penalties from the loan which may add to the cost of repaying early.
3) The interest is as monstrous now as when you agreed to it originally. It was your choice. When you are making a contract it is understood and assumed that you are capable of understanding the terms of that contract. You can't simply decide that it is now unfair because it is inconvenient to you.
As an aside, are you really and truly in a proper position to buy a property? You don't seem to understand the concept of interest and how it accrues. If you were to take out a mortgage, even with todays low rates you end up repaying half the amount of the mortgage again just in interest charges. There is a cost to borrowing - it has to be paid, elsewise why would anyone ever lend money?