Hi RickyD10,
To start, you CAN order an Enhanced Score Report, even for a 'cancelled' Score. Most Business Schools do NOT care if you take the GMAT more than once, so having more than one Official Score likely won't impact your applications at all. Assuming that your 2nd Official Score is significantly higher than your first, you can actually use that improvement to your advantage (as the two results would help to prove a number of positive character traits: you have the capacity to learn and improve, you don't give up, etc.).
If you've studied for just one week, then a 520 isn't too bad of a performance (the average score on the Official GMAT hovers around 540-550 most years). That having been said, raising a 520 to the point that you can consistently score 700+ will likely require at least another 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level. Based on your current timeframe though, you'll have no more than about 5 weeks of additional study time, meaning that there will likely be a limit to how much you can improve. By extension, if you truly "need" a 700+ Score to get into your first-choice School, then you'll almost certainly need to push back your Test Date.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on your timeline and your goals:
1) What study materials have you used so far?
2) What were the Quant and Verbal Scaled Scores for this 520?
3) When are you planning to apply to Business School and what Schools are you planning to apply to?
While the ESR doesn’t provide a lot of information, there are usually a few data points that we can use to define what went wrong on Test Day (and what you should work on to score higher). If you purchase the ESR, then I'll be happy to analyze it for you.
GMAT assassins aren't born, they're made,
Rich