Your card's credit limit will be lowered (temporarily).
our credit card limit will be lowered for a short period of time.
I(we) will lower your card limit temporarily.
「クレジットカードの限度額を(一時的に)下げる」= Your card's credit limit will be lowered (temporarily). / Your credit card limit will be lowered for a short period of time. / I(we) will lower your card limit temporarily.
ボキャブラリー
限度額 = credit limit / (credit) card limit
下げる = lower, be lowered
一時的に = temporarily / for a short period of time
これからの話なので「will」(未来を表す助動詞)を使う必要があります。