Problematic company

I have been renting cars for the past 5 years and never had any problem, on this occasion was very disappointing. It seems that renting with this company has cost me far way more then what I agreed to pay on the voucher that i presented.The staff are very kind ,but they do not know how to follow out agreement contracts,There were so many things that I had problems with this company from day 1 till now. I am now paying 6000 to a voucher that i have agreed to pay 3500 plus toll.They did not explain there was alot of confusion and my profile was mixed up .They basically did not follow the voucher and sold me insurance when i already paid for it when making my booking.I now understand why they did it ,but they did not go back to the voucher and sort it out. They were charging me for things that they did not explain and things that were not working on their rented cars.I am furious cause i am paying for, TOP UP WHICH WAS NOT EXPLAINED TO ME ,I THOUGHT IT WAS PART OF THE DEPOSIT I DID NOT KNOW THAT I AM ACTUALLY PAYING FOR THIS. I have contacted them and all they told me you signed for it that means you have to pay,so its not about customer service.I am still waiting from Economycarental