Either in case of emergency or just in need of urgent credit, you can always do so on your MTN SIM and then load to refund later. The steps and code to borrow MTN credit are discussed in this post.
How To Borrow Credit on MTN
It is also know as MTN XtraTime.
<1> Dial *606#
<2> Reply “2” (Request for xtratime)
<3> Reply with the digit in front of the amount you want to borrow
<4> Await the confirmation message and Click Here to check MTN borrowed credit balance
NOTE: The amount permitted per SIM depends on how frequent you load and amount loaded within the last 30 days.