Suzuki Gran Vitara

For about half a year I have been driving a Suzuki Gran Vitara Bj 1998. Now the car is already the second time (in the turn) on the opposite track, without reason (no wetness, no too fast driving etc.). It seemed to me as if the front wheels were blocking easily and the car just continues straight ahead. However, it could easily be steered back again. A familiar typed a gear damage, but can not confirm it 100%. Therefore my questions: it might be someone who has had similar experiences. (So I definitely don’t want to go any further) What should I do? Where can I get a gearbox cheaply…??? Thank you for the answers…. Best regards Lina