Unprofessional plumbing work

Not sure whether to say 'good morning' as there's absolutely nothing good about any morning ever since I moved into my house in 2018. I stay at no 27085 pongola street Protea glen ext 31 and ever since I moved in, I think I unblocked my toilet almost each and every 2 months. Plumbers assisting me informed me that it was because of a poor workmanship when they installed sewage pipes as they were not deep enough and when there's a blockage in the pipes waste will then push back and since my house is at the corner then it comes out of the heads inside my yard. I cannot even install drains inside my yard as there are not drains on the street and when it rains heavy my yard floods. Please I'm on my knees begging for you to assist me as this create harzadous environment for me and kids as we are forever breathing sewage.