Deducted amt from o/s

Dear All,
my question is suppose I am proprietor and my supplier supplies me machines and I owe to him Rs.5 lakh but when I recd their statement it's Rs.4.5 lakh and they mentioned one entry less Rs. 0.5 as I couldn't visit their Sri Lanka tour. that's why they deducted from outstanding Amt. so plz tell me what entry should I passed in my books of account?

Regards,
Samir Shaikh