Not applicable

Payment and JE upload into QB Enterprise

We have a payment log for ACH and wires with approximately 800 line items each month.  Also tons of JEs with multiple lines. I want to purchase a third party software to upload into QB Online. I called the support desk but not much help, they referred me to the apps store. I tried to use the IIF template but something when wrong and the JE upload duplicated my Account numbers and I don't know why.  There are so many vendors but I need advise on which app to chose.  Can anyone help?  Thanks.