I did an order with a store (in Israel) before Pesach. Before my order was processed I gave them my credit card information over the phone. My card was never charged. I emailed them, they said customer service would call me, but they never did. I emailed them again, but they never responded. How much effort am I mechuyav to put in to make sure they collect their payment? Thank you.
You don’t have to put in any more effort to try to pay them. The fact that they forgot to collect payment, makes your paying them Hashovas Aveida. Your obligation is to inform the owner of the lost object that he should come and get it, and if he does do so, you don’t have to run after him. However, if eventually they do come, even if it is after a number of years, you are obligated to pay them, Additionally you should write this down somewhere to remember that essentially you owe them this money.
CH:M 262-3 regarding Yiush Shlo M’daas. Regarding runnig after the owner see Kuntris Hashovas Aveida in the name of R’ M. Feistein zt”l, Pe’er Hador pg. 217 in the name of Chazon Ish, MIshpat Hoaveida 259 Shar Hatzion 13 in the name of R’ Eliyashiv zt”l, Hashovas Aveida Khilchoso 3-6.