Ethics behind using external excel freelancer to help with my thesis?
From what you've said in your question, it doesn't sound like there's a problem here. You said the information and the figures are your own, you've just had some assistance with making the data easier to work with.

It doesn't sound like what's been done is much different than if someone had pointed out that Excel already has a function that does what you were doing in a more streamlined fashion. Of course, this would be perfectly fine.

It's quite common for a student to have had the help of someone else in the course of working towards their thesis. This is particularly the case in technical matters like coding. You just have to make sure that you acknowledge their assistance appropriately (typically, by saying in your Acknowledgements that they provided assistance with your data). It's perfectly acceptable to get help from other people in your work. Seeking advice from people whose expertise is different to your own is an extremely common part of academic work. Where it becomes problematic is when you don't acknowledge that the advice came from someone else, and you (even inadvertently) pass it off as your own. I don't see that the fee changes this at all.

If you want to know for certain that this is acceptable then you should obviously ask your supervisor. Just explain the situation in full and ask "Is it okay to include this work in my thesis?" The thesis has not been submitted yet. So in the case that what you have done is inappropriate then no damage has been done. You would just ensure that the figures that appear in the thesis were not those that the freelancer produced.