PC controller issue: D-pad affects X-rotation

Recently, I discovered an issue with my PC controller(namely, Redgear Pro Wireless gamepad). Whenever I move forward in a game(left thumb stick up), the direction changes to the left and whenever I move backwards(left thumb stick down), direction changes to the right. So basically I move forward and left simultaneously, backwards and right simultaneously. The left thumb stick seems to be linked with the right thumb stick(which governs the direction of movement in most video games). Sometimes the controller works properly but most of the times it has this issue. The following screen shot of the game controller settings shows the problem in detail:

Controller Untouched:

When the left thumb stick up(notice how it affects the X-axis):

When the left thumb stick is down:

Now I thought this was a software issue, so I tried my controller in some other PC and unfortunately, I’m having the exact same issue. This seems to indicate that the issue is with the controller itself(i.e hardware issue). This has been bugging me for a while. I’ve tried to articulate my issue in the best way possible hoping that someone can provide a viable solution(I do not wish to purchase a new controller). In conclusion: please help!