XPS-13-9360 battery replacement - which one to buy?

Hi everyone, I have Dell XPS 13 (9360) TN-9360-N2-713S with TP1GT (TP1GT61) battery. So its "probably" the same as PW23Y. My laptop was working fine for 2,5 years, but now I can sometimes only get up to 2 - 4 hours in the best case scenario and sometimes even only 1-2 hours which is terrible. The only thing I use is the browser. I have gone through all recommendations over the internet (incl. Chrome Canary + media in flags, etc.), but that did not helped. BIOS marks my battery to be in "fair" state (same with Dell Power Manager) and therefore ready for the replacement. I have found out that Dell does not offer separate battery replacements online, because they will change it with some most likely very expensive additional cost for their work. There are also some guides over the internet and I have decided to change the battery myself. The main question is what battery I should buy and where? I am based in the Czech Republic so besides regular e-commerce sites I can also use e.g. Amazon (DE). There are many OEM versions from China (e.g. Cameron Sino) which are not recommended by users because of their quality. I have also noticed some problems with the compatibility and another bunch of frustrated users. Thanks.