讲到这个我就有经验，因为STEAM客服实在慢到有剩，又限制处理天数。
一开始跟你的状况一样，要我买礼物，然后我发现我要买的游戏不能买成礼物。
然后就跟他一阵攻防，然后他回我＂抱歉，您的情况不能退费＂。
我就回去翻STEAM的规范，翻到以下这句：
https://support.steampowered.com/kb_article.php?ref=9950-QYJZ-0797
Once you understand the terms of this offer completely,
immediately purchase the correct version of this game.
If Steam blocks your purchase because you already own a copy of the game,
purchase the correct version as a gift and store it in your inventory
for later.
简单讲就是，买错当下就去买正确的版本，
除非STEAM因为你已经购买过了不准你买，才去买礼物。
回他这句之后，他隔天就直接把$退到我的STEAM WALLET，也没等我买正确版本。
(注：因为即将超过15天处理期限，STEAM回一次都需要2~3天。)
供您参考。
※ 引述《sidakong (Kevin)》之铭言：
: 前几天特价时买了几个游戏，其中的Borderlands 2
: 因为破英文+没注意看，本来是想买Borderlands 2 goty
: 结果买到Borderlands 1 goty+Borderlands 2
: 进游戏缺东少西的才发现买错了
: 只好写信给Steam问看看能不能帮忙处理
: 等到回信如下：
: Thank you for contacting Steam Support.
: We apologize for the delay.
: Please purchase the intended game as a gift. Select the option "Store the gift in my inventory to send later".
: Please indicate when you have done so, and upon confirming your purchase on the account, I will cancel and refund your order for the original accidental purchase.
: To redeem this gift after the refund:
: -Place your cursor over your persona name at the top of the Steam interface, then click the 'Inventory' link.
: -Select the Steam tab. This will open the games/gifts that are currently in your Steam inventory.
: -Select the game that you would like to redeem onto your account. There should now be an 'Add to my game library...' button under the game's description.
: -Click 'Add to my game library...' to add the game to your Steam account. Once added the game cannot be removed from your account.
: Please note that if you originally purchased an item at a sale price and the sale has now ended, we cannot extend the previously discounted price for these items.
: This offer will only be valid for the next 15 days.
: 破英文看了一下
: 好像是说只要我把游戏转成礼物就可以帮我退掉
: 可是下面又有一堆步骤看无
: 看起来又不像是教我怎么把游戏转礼物
: 所以想问一下是不是把游戏转成礼物再回信就可以退掉？
: 另外很少用steam，要怎么把游戏转礼物呢？