Describe a recent problem you solved at work

Recently I have made a little progress in finding customers' WhatsApp numbers. From the first time I sent messages to customers to make contact until now, it has probably been 2 months. I've been so nervous about it for a long time. Then last weekend, I got one reply. It's just a small thing, but it proves my efforts are useful. And I learnt a lesson – the reason why experience is called "experience" is that it's a truly useful way to make things happen.