Hey, I am just filling in an application form and I have to describe my financial experience in previous jobs, can some one please check this for me? I don't know if its ok to write in past continues? or shall i change to present perfect continues? and can i mix them? Please help..

While I was working as an estate agent at BOC Property in London some of my responsibilities included checking and controlling tenants’ rent payments. Every week I was checking our bank statements in order to see whether payments of over a 120 tenants have been made and keying them all into the system. In case the payments were missing I was requesting a proof of payment from tenants and dealing with it appropriately. I was also responsible for making payments to gas and electricity suppliers as some of our properties had utilities included in the rent.
I was also performing financial operations at AEG in London. After investigating PPI claims, using a PayPrep system I was issuing compensation cheques on a daily basis.
At DHL in London I was creating financial invoices on a daily and monthly basis. I was also responsible for imposition of financial penalties on the drivers.