Gabriel buys a van that costs $R840000.$ He pays a $20\%$ deposit and takes a loan to repay the remainder. The terms of the loan are as follows:

Interest rate: $12\%$ per annum compounded monthly.

Duration: $7$ years.

What is Gabriel's monthly instalments to pay off the loan?

A$.R10843\mathrm{.}77$

B$.$ R $14840\mathrm{.}98$

C$.$ R $11862\mathrm{.}64$

D$.$ R $12376\mathrm{.}92$