Yes there are other lenders that dont use valex, but I suggest valex isnt the problem, more that the new valuation wasnt performed by the same valuer as the original (unless of course house prices have dropped 20% in your area?).
Have a chat to the lender or broker that you are using and see if they can sort it out. At least get the valuation company names. If they are unwilling, get a second opinion from another broker who can get an upfront valuation with a different valuer.