Myphone Infinity II Lte (Cube) - Replacement for the BM-11 battery

Good evening.
I am (un) happy to own a Myphone Infinity II Lte phone.
Unfortunately, as with all other models, the battery begins to seriously fail. So much so that I am basically tied to power banks, which - due to what I do - I cannot always have connected to the phone (skipping over the fact that it is inconvenient).

The problem is, it's not quite possible to buy the battery model I need. There are two sellers on the Allegro. One sells used for PLN 80, the second new one for almost PLN 1,200 (sic!)

Due to the fact that the phone is of Polish production, nowhere outside our homeland you can not buy this phone, and parts for it even more.
The producer is not eager ...

So I am asking for help in finding a replacement. The battery you are looking for is:
Model: BM-11
Dedicated to: Myphone infinity II Lte, Myphone Cube Lte
Type: Lithium Ion
Rated data: 3.8V, 2000mAh, 7.6Wh, maximum charging voltage 4.35V
Dimensions (approx.) 8.3 x 5.3 x 0.4 [cm]
Catalog number: AKGAKMYPBCUBL001_682
EAN code: 5900495461360

Thanks in advance for your help and tips.

greetings

Look here and only a replacement, sometimes good art is found.
https://tanieakoszenia.pl/baterie-c-2_37_38.html

Quote:

Temporarily unavailable

Like on any other website of this type.

Well, unless you mean some other model. If so, thank you in advance for giving it, because I do not know one: /

Ask at Teletorium stands, if they won't have them, they can always order.