I read this on another forum, when applying for FLR or ILR, dont leave it to the last minute when applying for a visa, if there is a problem, the price is too high to pay.. ... dont let it happen to you

"For various reasons we applied on the 2nd of April for LTR as my spouse using form FLR(M), and unfortunately my payment card rejected and I had to resend and this application was processed on the 21st April (31 days late). Hence at the time of the application my wife's LTR had expired. on this basis the application was rejected with no grounds to appeal, and she was told she must leave the country ASAP but with no deadline given."

the cost, the visa fee you just paid, cost of air tickets and having to apply again, also being away from your wife/husband..