my tecno R7 brings no service whenever I switch my network to 3G only on both the simcard ports , but when its on dual mode it gives me 3G but fluntuates between 2g n 3g, * it won't stay on ordinary 3G * pls what can I do ?

Pls help me i can't use lucky patcher on my infinix zero and it's been rooted and SuperSU is installed, if I try to patch any app it keeps saying "don't have access to sd card from root pls update it binary or SuperSU* and I have upgraded all ..