3 sentences

1. 如果逾期未还，利息将会加倍。

   rú​guǒ yú​qī wèi huán, lì​xī jiāng huì jiā​bèi.

   If it is not repaid on time, the interest will double.

   Source: Dong Chinese Dictionary

2. 您的还款已经逾期，请尽快处理。

   nín de huán​kuǎn yǐ​jīng yú​qī, qǐng jǐn​kuài chǔ​lǐ.

   Your payment is overdue; please handle it as soon as possible.

   Source: Dong Chinese Dictionary

3. 由于多次逾期还款，他的信用受到了影响。

   yóu​yú duō cì yú​qī huán​kuǎn, tā de xìn​yòng shòu​dào le yǐng​xiǎng.

   His credit has been affected due to several late repayments.

   Source: Dong Chinese Dictionary