The last shirts I bought were from Charles Tyrwhitt. I always wait for their promotions to come round and then I take full advantage. They are expensive but that's for a reason. The quality far outreaches any other retailers in my opinion.
My last order consisted of three shirts: white, blue, and pink. These were double cuffed; the ones you wear with lovely cuff links. Great for work.
The delivery was thrown in for free since I spent around £70. I ordered the shirts on their website and they arrived with four days which I was fairly impressed with. I wasn't in any great hurry for them, so that was fine. You could pay for next day delivery, but I had already spent enough money and was happy to wait to receive them.
The fit was perfect for me. What's more, is that they wash and iron really nicely too. Some shirts are a mission to get the creases out of, but the material is top-notch.
I have never had to return any products or contact customer services so I cannot comment on either of these. However, judging by their facebook pages it seems their team is quick to respond to any queries and comments.
I would have no hesitation in recommended their products. I have been buying shirts from here for over 20 years and no doubt many more to follow.