@Lakeof Red, I feel like your attitude is really poor.
You've listed the following bugs... did you even read them?
https://github.com/Scirra/Construct-3-bugs/issues/580
That's a bug in Chrome.
https://github.com/Scirra/Construct-3-bugs/issues/1277
That one was addressed and fixed?
https://github.com/Scirra/Construct-3-bugs/issues/1313
That's a 5-day old issue and the company has already assigned someone to look at it.
You really couldn't have picked worse examples.
Frankly, you come across as really unprofessional.
Also, you may want to read up on UK law. You are not entitled to a refund just because you changed your mind. You must give the supplier the opportunity to repair the issue. If you're not willing to send a reproducible example of the problem, be it your own source or a minimal example, they are under no obligation to refund you.