FWIW I recall that VHS was about 400 whereas SVHS was 600 - so nothing like HD at 1080x1920 ( you may need to search for the quality-factors, but VHS was not that good, being an analogue it was almost impossible to EDIT, without obvious degredation.
A commercial outfit will be an expensive choice, but if the tapes are treasured - maybe worthwhile. FWIW, I'd be reluctant to send the originals anywhere by post.
Another means is to use a DVD Recorder ( now rare!) which can accept both SCART and SVHS inputs recording to HDD - simple Edits can remove obvious breaks... then convert to a DVD - not the highest quality.... but better than the analogue was originally. Also Once in digital form, you can apply Colour correction, add music, adjust brightness add Titles and generally "Clean-up" the original.
If the originals are commercial movies, there may be a copyright issue, but I'm sure you know this already.
BTW do wind-rewind the tapes before playing - just to make sure they are free-running.
Good Luck