Where to apply for UCAS

Hi,
I am a post year 13 student hoping to retake my A-levels and re apply through UCAS. I am currently struggling to find any reputable or trustworthy sites which can offer predicted grades and references. I am confident in my ability with the personal statement and although it would help if the same service provide for final exams next summer, I am open to finding an external source.
Currently I have found two centres each with their own advantages, but also things that would make one doubt their credibility.
Exam Centre London is a very promising one, allowing predicted grades from AS papers and the guarantee of a reference and support. However upon talking to peers and past applicants, I have found out that they are slow with the reference and cause issues with the applications.
Tutors and Futures is the second site, which although have no direct red flags, I still question how reliable their predictions are. They use a portfolio of work which is collated from students past papers to determine a predicted grade. This is promising and relatively easy, however I have to ask would a University look into such an institution and question the reliability of their predictions, ultimately causing more problems with our applications.
If anyone knows of these institutions and have had good experiences with them, a reply with your own experience would be appreciated. At the same time it would be great to hear from other second round reapplicants, to hear and find out if there are other more reliable places i can process my UCAS application.
Many thanks!