Solved

Buy parts but didn't add them correctly.

What did you try to do?
Having 4 parts I bought 10 for 7 tokens.

What happened instead?
Expected value: 14 parts
Actual value: 10 parts

Did the problem happen while using wi-fi, mobile data, or both?
Wi-fi

Did the bug happen in the app, on PC, or both?
PC

What operating system is your PC?
Windows 10

Which browser did you experience the problem in?
Chrome

Can the bug be reproduced?
No.

Additional comments:

I have flagged this to support.

Hello Javier,

I'm so sorry for the inconveniences.

I have sent you the parts and 5 tokens to make up for the inconveniences that this has caused you.

Please let me know if I could be of any further help.

Hi, we believe we determined what the issue was and it has now been patched and will work in the future.

The patch went live from 3pm UTC 4th February 2020